Over the past twelve years, Six Flags Great Adventure in Jackson has imported dozens of animals, from antelopes to tigers to zebras, sometimes through donation and sometimes through outright purchase, to support its popular safari.

But at least nine of those imports may have been illegal, according to federal communications and records, because the park operated without a valid Captive Bred Wildlife (CBW) permit.

A CBW permit is required for the interstate trade of exotic animals listed as endangered or threatened in the wild, and born in captivity in the United States, according to David Favre, who teaches animal law at Michigan State University. The permit, issued by the U.S. Fish and Wildlife Service under the Endangered Species Act, allows the park to specifically buy and sell African elephants, Siberian tigers and red lechwes, a type of antelope known for their long, spiraled horns, as long as the trade is done for the survival of the species.

Yet there appears to be a gaping hole in the park’s permit history: Federal records show no evidence of any CBW permit on file since 2007. The last permit on file for Six Flags expired in 2007, according to separate state records.